Previously active noise cancellation (ANC) systems and hearing aids have not been used in combination. ANC and hearing aids work in opposite ways, since a hearing aid amplifies sound and ANC attenuates sound. But by combining a hearing aid and an ANC in a suitable way as in this invention, it is possible to obtain the advantages and technical effects of both systems.
WO05052911 relates to a hearing aid which can perform active noise cancellation. The hearing aid includes a signal processor which produces a compensation/cancellation signal that can attenuate acoustic signals that bypasses the signal path of the hearing aid and enters the ear canal.
DE 1033219 also relates to a hearing aid which can perform active noise cancellation. The active noise cancellation is performed by processing signals from one or more microphones and loudspeakers arranged in the hearing aid vent. The microphone signals are transmitted to a filter unit in order to attenuate unwanted acoustic signals.
WO06003618 relates to an earplug with a circuit for active noise cancellation. When a noise signal is received in the earplug, a cancelling signal is processed by means of the circuit to cancel the noise signal.
U.S. Pat. No. 6,567,524 concerns a hearing protective earplug with an audio communication terminal for obtaining speech signals of high quality while attenuating noise. The earplug performs noise attenuation automatically adapted to the noise conditions and communication modes.
U.S. Pat. No. 6,181,801 and U.S. Pat. No. 6,021,207 relate to a communications earpiece which receives audio signals, wired and wireless, respectively, sent from an external device such as a mobile phone. Ambient sounds are used for noise cancellation. The communications earpiece can be used by both hearing impaired and non-hearing impaired users.
When a hearing device user is in a noisy environment, it is advantageous that the hearing device can perform active noise cancellation. But it is a problem of the prior art that when the hearing device operates as active noise cancellation, sound signals, both the undesired and the desired, will be attenuated due to the active noise cancellation. This may not always be desirable.
It therefore remains a problem to provide a hearing device which improves active noise cancellation (ANC) and thus may provide a better audible signal to the user.